1. Field of the Invention
The present invention relates to an electron emission source, an electron emission device using the same, and a composition for the same.
More particularly, the present invention relates to an electron emission source that may exhibit enhanced electron emission performance, an electron emission device using the same, and a composition for the same.
2. Description of the Related Art
Typically, electron emission devices include an anode and a cathode, and an electron emission source that is electrically coupled to the cathode, e.g., by being disposed on the cathode. Of course, multiple electron emission sources, anodes and cathodes may be provided. A voltage may be applied across the anode and the cathode to form an electric field between the anode and the cathode, in order to cause the electron emission source to emit electrons. The electric field developed between the anode and the cathode may direct the emitted electrons to collide with a phosphor or other electroluminescent material, causing the material to emit light, e.g., visible light.
The electron emission source may include a carbon-based material.
Carbon-based materials, e.g., carbon nanotube (CNT), may exhibit various advantages such as good electron conductivity, high field enhancement effect, a low work function, good electron emitting characteristics, etc.
Furthermore, the use of a carbon-based material may allow the device to be operated at low voltage and manufactured in large area sizes, which may be desirable for a large display or other light-emitting device such as a lamp. Therefore, electron emission sources incorporating carbon-based materials may be desirable for electron emission devices.
Electron emission sources that include CNTs may be fabricated by growing CNTs on a substrate using a chemical vapor deposition (CVD) process, by a paste method that includes applying an electron emission source composition that includes CNTs to a substrate, etc. When the paste method is used, a manufacturing cost may be low, and electron emission sources may be formed across a large-area device.
When paste is prepared using CNTs, some silver powder, etc., may be added to the paste as filler. Adding silver powder may improve contact between CNTs and/or improve contact between the CNTs and the substrate. In addition, the CNT may be less separated from the substrate during use, and thus the electron emission property and lifetime of the CNT electron emission sources may be enhanced.
Despite the advantages of using a silver powder, when silver powder is added to the CNT as a filler, the permittivity of the CNT may be low. Additionally, it may be desirable to use a filler having a relatively low dielectric constant, because reducing the dielectric constant of the filler may improve the electron emission performance of the electron emission device.